1. Field of the Invention
The present invention relates to a modular semiconductor device comprising a plurality of collectively mounted IC packages.
2. Description of the Related Art
FIG. 1 is a partially broken away perspective view which illustrates a package called an SOP (Small Outline Package) for conventional semiconductor devices usually called ICs.
FIGS. 2A to 2E illustrate a conventional hybrid integrated circuit device called a module employing the SOP-type IC package. FIG. 2A is a top view, FIG. 2B is a front elevational view, FIG. 2C is a side elevational view, FIG. 2D is a bottom view, and FIG. 2E is an enlarged view which illustrates the portion A of FIG. 2C.
Referring to FIG. 1, an IC package 1 includes a semiconductor chip 2, leads extending outwardly from the semiconductor chip 2, and the like are sealed by resin 4 and outer leads 3 to be connected to external equipment (omitted from illustration) extend outwardly from the resin. Referring to FIGS. 2A to 2E, a hybrid IC semiconductor device 5 called the module is constituted by mounting, on an electronic circuit board 6, a plurality of the IC packages 1 and other chip parts 7, such as chip resistors, chip condensers, and the like. A land 8 formed on the electronic circuit board 6 has an electrode 8a for mounting the IC packages and chip parts 7 and also has an external I/O electrode 8b for establishing an electrical connection between the electronic circuit board 6 and external equipment. A chip lead 9 supports the module 5 on the external equipment or on an external board and also establishes an electrical connection of the above-described components. The clip lead 9 comprises a clip portion 9a connected to the external I/O electrode 8b and clipped to the electronic circuit board 6 and a lead portion 9b to be inserted into an electrode or a through hole of the external equipment or the external board. Solder 10 establishes an electrical connection between the outer lead 3 of the IC package 1 or the electrode of the chip parts 7 and the electrode 8a on the electronic circuit board 6 or a connection between the external I/O electrode 8b on the substrate 6 and the clip lead 9.
As a result of the structure of the conventional module 5 comprising a conductor pattern (omitted from illustration) made of copper foil or the like, the IC package 1 and the chip components 7, each of which is formed on the electronic circuit board 6, a function which has been impossible for a single IC package 1 to possess is produced. For example, the conventional module 5 can be used as a semiconductor device having a memory or the like whose storage capacity has been enlarged or used as a semiconductor device comprising a plurality of IC packages 1 of different types and thereby having hybrid functions.
However, since the conventional modular semiconductor device is structured as described above, the ICs 1 and the chip parts 7 are able to be mounted on only obverse and reverse sides of the electronic circuit board 6. In the present electrical and electronic industries, the mounting density (usually called the packaging density) of the ICs 1 and the chip parts 7 is desired to be increased. However, the packaging density on the conventional module 5 can, at most, be tripled since the ICs 1 and the chip component 7 can be mounted only on both sides of the module 5. Therefore, packaging density of conventional modules is limited.
In addition, it has been difficult for a user to enlarge the memory capacity of the conventional modules and to expand the functions of the same. For example, the module 5 must be replaced in the above-described case because the user cannot expand it.